.TH std::log10(std::valarray) 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::log10(std::valarray) \- std::log10(std::valarray)

.SH Synopsis
   Defined in header <valarray>
   template< class T >
   valarray<T> log10( const valarray<T>& va );

   For each element in va computes common (base 10) logarithm of the value of the
   element.

.SH Parameters

   va - value array to apply the operation to

.SH Return value

   Value array containing common logarithms of the values in va.

.SH Notes

   Unqualified function (log10) is used to perform the computation. If such function is
   not available, std::log10 is used due to argument-dependent lookup.

   The function can be implemented with the return type different from std::valarray.
   In this case, the replacement type has the following properties:

     * All const member functions of std::valarray are provided.
     * std::valarray, std::slice_array, std::gslice_array, std::mask_array and
       std::indirect_array can be constructed from the replacement type.
     * For every function taking a const std::valarray<T>&
       except begin() and end()
       \fI(since C++11)\fP, identical functions taking the replacement types shall be added;
     * For every function taking two const std::valarray<T>& arguments, identical
       functions taking every combination of const std::valarray<T>& and replacement
       types shall be added.
     * The return type does not add more than two levels of template nesting over the
       most deeply-nested argument type.

.SH Possible implementation

   template<class T>
   valarray<T> log10(const valarray<T>& va)
   {
       valarray<T> other = va;
       for (T& i : other)
           i = log10(i);

       return other; // proxy object may be returned
   }

.SH Example


// Run this code

 #include <cmath>
 #include <iomanip>
 #include <iostream>
 #include <valarray>

 void show(char const* title, const std::valarray<float>& va)
 {
     std::cout << title << " : " << std::right;
     for (float x : va)
         std::cout << std::setw(6) << x;
     std::cout << '\\n';
 }

 int main()
 {
     const std::valarray<float> n{-2.f, -1.f, 0.f, 1.f, 2.f, 3.f, INFINITY};
     const std::valarray<float> pow10{std::pow(10.f, n)};
     const std::valarray<float> log10_pow10{std::log10(pow10)};

     show("n      ", n);
     show("10ⁿ    ", pow10);
     show("lg(10ⁿ)", log10_pow10);
 }

.SH Output:

 n       :     -2    -1     0     1     2     3   inf
 10ⁿ     :   0.01   0.1     1    10   100  1000   inf
 lg(10ⁿ) :     -2    -1     0     1     2     3   inf

.SH See also

   log(std::valarray)  applies the function std::log to each element of valarray
                       \fI(function template)\fP
   log10
   log10f              computes common (base 10) logarithm
   log10l              (\\({\\small\\log_{10}{x}}\\)log[10](x))
   \fI(C++11)\fP             \fI(function)\fP
   \fI(C++11)\fP
                       complex common logarithm with the branch cuts along the negative
   log10(std::complex) real axis
                       \fI(function template)\fP

.SH Hidden category:
     * Pages with unreviewed LWG DR marker
